Needle breakage safety device

ABSTRACT

A device for disengaging the sliding carriage of a knitting machine is response to a needle break. The high amplitude sound caused by a break is sensed by a microphone attached to the machine frame, and the amplified output of the microphone toggles a threshold trigger whose amplified output energizes an electromagnet. The latter releases a spring biased lever which in turn moves a shift rod to disengage the carriage drive. Means are also provided for deactivating the safety device when the carriage leaves the needle region, thereby preventing triggering from the noise caused by racking or carriage reversal.

United States Patent [191 Schieber et al.

[ Dec. 25, 1973 NEEDLE BREAKAGE SAFETY DEVICE [75] Inventors: Hans Schieber; Erich Krause, both of Bopfingen, Germany [22 Filed: Nov. 10, 1972 211 App]. No.: 305,39 s

[.30] Foreign Application Priority Data Feb. i0, [972 Germany P 22 06 363.4

[52] US. Cl. 66/165, 66/157 [51] Int. Cl D04b 35/10 [58] Field of Search 66/137, 165; 26/63; ZOO/61.01

[56] References Cited UNITED STATES PATENTS 2,085,198 6/l937 Lindsay ZOO/61.01

2,957,957 l0/l960 Johnson 200/6l.0l 3,247,339 4/1966 Miller ZOO/61.01 I 3,528,l45 9/1970 Troope et al. 26/63 Primary ExaminerRonald Feldbaum Attorney-Richard C. 'Sughrue et al.

[ 5 7 ABSTRACT A device for disengaging the sliding carriage of a knitting machine is response to a needle break. The high amplitude sound caused by a break is sensed by a microphone attached to the machine frame, and the amplitied output of the microphone toggles a threshold trigger whose amplified output energizes an electromagnet. The latter releases a spring biased lever which in turn moves a shift rod to disengage the carriage drive. Means are also provided for deactivating the safety device when the carriage leaves the needle re gion, thereby preventing triggering from the noise caused by racking or carriage reversal.

8 Claims, 7 Drawing Figures PATENTED DEC 25 I975 SHEET 1 [IF 4 PATENTEU UEC25 I975 13; 780.542

SHEET U UF 4 NEEDLE BREAKAGE SAFETY DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle breakagev safety device on knitting machines, said device responding to .a shockwave occurring when a needle breaks and switching the disengaging device for the sliding carriage of the knitting machine via an electronic amplifier.

2. Prior art To safeguard against damage resulting from needle breakage, knitting machines, more particularly straight and circular knitters, are generally provided with safety devices which either switch off the knitting machines after needle breakage or prevent the sliding carriage from passing through again in order to avoid any further breakage of needle feet. Such further breakage may result from damage which occurred when the first needle broke. Stopping the carriage also avoids any damage to the upper and lower needle beds, or in the case of a rotary knitting machine, to the cylinder or rib disc.

Safety devices operating on the principle of an impact safety mechanism have previously been used with straight and circular knitting machines. In such safety devices overload levers are mounted on the sliding car,- riage entrainment of the drive means. The shock-from the breakage of a needle causes these levers to tilt sideways and to activate an electrical disengaging device.

In knitting machines having additional selecting in struments for the needles, for example several rows of Jacquard rods, the force needed to pull the sliding carriage over the needles and rods is considerable/Furthermore, the sliding carriage of a knitting machine of this type is heavier than that of a less complicated machine. The entrainment force and the inertiaof the moving sliding carriage are so great that it is no longer possible to release the disengaging device by the aboveme'ntioned impact safety device as a result, for example, of the relatively small shock caused by the breakage of only one needle.

A known safety device intended to solve this problem comprises devices mounted on each needle bed of a straight knitting machine. These devices transmit the impact produced by the needle breakage to a diaphragm by means of a free swinging weight. The diaphragm itself releases switches for activating the disengaging devicefor the sliding carriage of the machine. With this type of safety device at least two monitoring devices are required for each knitting machine, since one monitoring device has tobe mounted on each needle bed in the direction from which the shock resulting from needle breakage will come. This safety device is not suitable for rotary knitting machines.

SUMMARY OF THE INVENTION The object of the present invention is to obviate the disadvantages of known needle breakage safety devices and to create a simple and reliable needle breakage safety device which may be used for both straight and.

rotary knitting machines.

This problem is solved according to the invention with a needle breakage safety device wherein a microphone is mounted on the members of the'knitting machine bearing the needle beds to pick up. sound waves. The microphone is connected toan electronic switch- 2 ing circuit responding to the high amplitude produced by a needle breakage,-and the switching circuit is connected to the disengaging device for the knitting machine.

The device according to the invention is simple in construction and has the advantage that the sound waves can be monitored by a microphone mounted in a desired position and in a desired direction on the member bearing the needle beds. The high amplitude caused by the needle breakage causes the electronic switching circuit to trigger and this in its turn activates the disengaging device by way of an electronic amplifier or relay.

In a rotary knitting machine the microphone is advantageously attached to the member about which the cylinder and rib disc of the knitting machine'r'otate.

The electronic switching circuit is advantageously a bistable stage with follow up amplification, for example, in the form of a relay.

An advantageous development of the needle breakage safety device according to the invention consists in that a switching device is provided for the synchronized interruption of the connection between the microphone and the disengaging device each time the sliding carriage leaves the region of the needles.

In this way the disengaging device is prevented from being released andthe' knitting machine from being switched off as a result of the noises produced by the switching of the sliding carriage orthe racking mechanisms on straight knitting machines.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are represented in the drawings and these will now be described in more detail. In the drawings:

FIG. 1 is a front view of a straight knitting machine;

FIG. 2 is a side view of a needle board of a straight knitting machine with'a sliding carriage disposed on it and provided with a microphone;

FIG. 3 is a perspective view of a rotary knitting machine having a microphone attached to it;

FIG. 4 shows a normal sound wave and a high amplitude wave which occurs suddenly as a result of 'a needle breakage;

FIG. 5 is a block diagram of the electronic circuit between the microphone and the disengaging device;

FIG. 6 shows an electromagnetic device for releasing the disengaging device in the blocked state, and

FIG. 7 shows the device of FIG. 6 in the released state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a front view' of a straight knitting machine to which the needle breakage safety device according to the invention can be applied. A sliding earriage 13 is connected-to a chain 14. The chain 14 is driven by a chain wheel 15, which is connected via coupling means (not shown) to a drive mechanism (not shown).

As may be seen more clearly from FIG. 2, which shows a side view of a needle bed having a sliding carriage disposed on it, a needle bed support 1 is attached to the machine frame 16. A microphone 2, which receives sound waves transmitted by the needle bed, is mounted on the needle bed support 1. These sound waves are produced by the passage of the needles and rods through the lock in the sliding carriage 13. They are picked up by the microphone 2 and converted into electrical signals or oscillations. A high amplitude oscillation occurs when a needle breaks. This leads to the releasing of the disengaging device for the sliding carriage of the knitting machine in order to prevent further damage to the needles and the needle beds by the passage of the sliding carriage subsequent to the first needle breakage.

FIG. 4 shows a time plot .of a sound oscillation which may occur in the needle bed support 1. The reference number represents a high amplitude oscillation which is produced in the needlebed support 1 when a needle breaks. As stated above, this high amplitude oscillation 5 is sensed by the microphone 2 and used to release the disengaging device for the sliding carriage.

To prevent the disengaging device from being released by sounds occurring, for example, when the sliding carriage 13 or the racking mechanism on the knitting machines is switched, a switching device is provided for the synchronized interruption of the connection between the microphone 2 and the disengaging device each time the sliding carriage leaves the region on the needles. In FIG. 1 the region beyond the needles is designated by x. When the sliding carriage 13 passes a timing point 17 in the region beyond the needles the connection between the microphone or monitoring device 2 and the disengaging device for the sliding carriage is broken. When the sliding carriage enters the region containing the needles the interrupted connection is restored. In this way the sounds produced during the switching of a racking mechanism or by the sliding carriage stops, for example, do not release the disengaging device unnecessarily when the sliding carriage 13 is positioned beyond the region of the needles.

:FIG. 3 shows a perspective view of a rotary knitting machine in which a microphone 2 is mounted on a member 1 about which the cylinder and the rib disc of the rotary knitting machines rotate.

FIG. 5 shows a block diagram of an electrical circuit. The disengaging device for the sliding carriage of the knitting machine is released by way of this circuit in response to a high amplitude oscillation 5 picked up by the microphone 2. The microphone is connected via an electronic amplifier 6 to a bistable stage 7 in the form of a Schmitt trigger switch-having an adjustable threshold value. The bistable stage 7 acts on a relay 8, which in turn acts on an electromagnet 9 of the disengaging device for the sliding carriage via a switch 3.

The sound oscillations produced during the passage of the needles and rods through the lock of the sliding carriage 13 are also picked up by the microphone 2 and converted into electrical oscillations. The bistable stage 7, whichreceives its input from the electronic amplifier 6, is held in its one position as long as the sound oscillations 4 are constant and do-not exceed the thresholdlevel shown in FIG. 4. When a higher amplitude oscillation 5 is produced as a result of the breakage of a nee-- dle foot, the bistable stage 7 switchesinto its second 1 sliding carriage 13 to a standstill. The connection between the microphone 2 and the disengaging device is interrupted in synchronism with the knitting machine operation each time the sliding carriage leaves the region of the needles and it is restored again when the sliding carriage 13 enters the region of the needles.

In FIG. 6 the part of the disengaging device which follows the switch 3 is represented in the closed state.

stage thus releasing a current flow, which is transferred The electromagnet 9, which is supplied with power via the switch 3, is mounted on the machine frame 16. It acts on a lever 10 which holds a spring-loaded lever 11 against the spring tension as long as the electromagnet is not energized. When the spring-loaded lever 11 is in this position a shift rod 12 is held in such a position that a coupling (not shown) connected to the chain wheel 15 is engaged.

When a high amplitude oscillation 5 occurs the relay 8 is energized as described above and the electromagnet 9 is supplied with power when the sliding carriage 13 is situated in the region of the needles. As a result, the lever 10 is attracted and the lever 11 is released whereby the lever 11 can be moved according to the initial stressing of its spring ans the shift rod 12 is moved in the direction of the arrow in FIG. 7. The movement of the shift rod 12 releases the coupling (not shown), and the sliding carriage 13 is brought to a standstill. The released position of the device shown in FIG. 6 is represented in FIG. 7.

What is claimed is:

1. In a needle breakage safety device for knitting machines including a needle bed support member, a movable carriage cooperable therewith, drive means for the carriage, means responsive to a needle break for producing an electrical signal, means for amplifying the signal, and means responsive to the amplified signal for disengaging the drive means from the carriage, the im provements characterized by:

the means responsive to a needle break for producing an electrical signal comprising a microphone mounted on the needle bed support member for sensing the high amplitude sound caused by a needle break, and an electronic threshold switching circuit for producing an output only in response to such high amplitude sound, said output being connected to the amplifying means.

2. A safety device as defined in claim 1 wherein the switching circuit comprises a bistable stage having an adjustable threshold level.

3. A safety device as defined in claim 1 wherein the amplifying means comprises an electrical relay.

4. A safety device as defined in claim 2 wherein the amplifying means comprises an electrical relay.

5. A safety device as defined in claim 1 further comprising means'synchronized with the movement of the carriage for disabling the safety device whenever the carriage leaves the region of the needles.

6. A safety device as defined in claim 4 further comprising means synchronized with the movement of the carriage for disabling the safety device whenever the carriage leaves the region of the needles.

7. A safety device as defined in claim 1 wherein the disengaging means comprises an electromagnet energizedby the amplifying means, a pivotally mounted releasing lever adapted to be rotated by the electromagnet, a pivotally mounted, spring biased shift lever held in a first position by the releasing lever and rotatable to a second position upon release, and a shift rod displacenet, a pivotally mounted, spring biased shift lever held in a first position by the releasing lever and rotatable to a second position upon release, and a shift rod displaceable by the shift lever for disengaging the carriage drive means when the shift lever rotates to its second positlon. 

1. In a needle breakage safety device for knitting machines including a needle bed support member, a movable carriage cooperable therewith, drive means for the carriage, means responsive to a needle break for producing an electrical signal, means for amplifying the signal, and means responsive to the amplified signal for disengaging the drive means from the carriage, the improvements characterized by: the means responsive to a needle break for producing an electrical signal comprising a microphone mounted on the needle bed support member for sensing the high amplitude sound caused by a needle break, and an electronic threshold switching circuit for producing an output only in response to such high amplitude sound, said output being connected to the amplifying means.
 2. A safety device as defined in claim 1 wherein the switching circuit comprises a bistable stage having an adjustable threshold level.
 3. A safety device as defined in claim 1 wherein the amplifying means comprises an electrical relay.
 4. A safety device as defined in claim 2 wherein the amplifying means comprises an electrical relay.
 5. A safety device as defined in claim 1 further comprising means synchronized with the movement of the carriage for disabling the safety device whenever the carriage leaves the region of the needles.
 6. A safety device as defined in claim 4 further comprising means synchronized with the movement of the carriage for disabling the safety device whenever the carriage leaves the region of the needles.
 7. A safety device as defined in claim 1 wherein the disengaging means comprises an electromagnet energized by the amplifying means, a pivotally mounted releasing lever adapted to be rotated by the electromagnet, a pivotally mounted, spring biased shift lever held in a first position by the releasing lever and rotatable to a second position upon release, and a shift rod displaceable by the shift lever for disengaging the carriage drive means when the shift lever rotates to its second position.
 8. A safety device as defined in claim 6 wherein the disengaging means comprises an electromagnet energized by the amplying means, a pivotally mounted releasing lever adapted to be rotated by the electromagnet, a pivotally mounted, spring biased shift lever held in a first position by the releasing lever and rotatable to a second position upon release, and a shift rod displaceable by the shift lever for disengaging the carriage drive means when the shift lever rotates to its second position. 